The avocado (Persea americana) is a tree native to Central Mexico, classified in the flowering plant family Lauraceae along with cinnamon, camphor and bay laurel. Avocado or alligator pear also refers to the fruit (botanically a large berry that contains a single seed) of the tree, which may be pear-shaped, egg-shaped or spherical.
Avocados are commercially valuable, and are cultivated in tropical and mediterranean climates throughout the world, producing a green-skinned, pear-shaped fruit that ripens after harvesting. Trees are partially self-pollinating and often are propagated through grafting to maintain a predictable quality and quantity of the fruit.
Culinary uses
The fruit of horticultural cultivars has a markedly higher fat content than most other fruit, mostly monounsaturated fat, and as such serves as an important staple in the diet of various groups where access to other fatty foods (high-fat meats and fish, dairy, etc.) is limited.
A ripe avocado yields to gentle pressure when held in the palm of the hand and squeezed. The flesh is prone to enzymatic browning; it turns brown quickly after exposure to air. To prevent this, lime or lemon juice can be added to avocados after they are peeled.
The fruit is not sweet, but fatty, and distinctly yet subtly flavored, and of smooth, almost creamy texture. It is used in both savory and sweet dishes, though in many countries not for both. The avocado is very popular in vegetarian cuisine, as substitute for meats in sandwiches and salads because of its high fat content.
Generally, avocado is served raw, though some cultivars, including the common Hass, can be cooked for a short time without becoming bitter. Caution should be used when cooking with untested cultivars; the flesh of some avocados may be rendered inedible by heat. Prolonged cooking induces this chemical reaction in all cultivars.
It is used as the base for the Mexican dip known as guacamole, as well as a spread on corn tortillas or toast, served with spices.
In the Philippines, Brazil, Indonesia, Vietnam, and south India (especially the coastal Kerala and Karnataka region), avocados are frequently used for milkshakes and occasionally added to ice cream and other desserts. In Brazil, Vietnam, the Philippines and Indonesia, a dessert drink is made with sugar, milk or water, and pureed avocado. Chocolate syrup is sometimes added. In Morocco, there is a similar chilled avocado and milk drink, that is sweetened with confectioner’s sugar and hinted with orange flower water.
In Ethiopia, avocados are made into juice by mixing them with sugar and milk or water, usually served with Vimto and a slice of lemon. It is also very common to serve layered multiple fruit juices in a glass (locally called spreece) made of avocados, mangoes, bananas, guavas and papayas. Avocados are also used to make salads.
Avocados in savory dishes, often seen as exotic, are a relative novelty in Portuguese-speaking countries, such as Brazil, where the traditional preparation is mashed with sugar and lime, and eaten as a dessert or snack. This contrasts with Spanish speaking countries, such as Mexico or Argentina, where the opposite is true and sweet preparations are often unheard of.
In Australia and New Zealand, it is commonly served in sandwiches, sushis, on toast, or with chicken. In Ghana, it is often eaten alone in sliced bread as a sandwich. In Sri Lanka, well ripened flesh, thoroughly mashed with sugar and milk, or treacle (a syrup made from the nectar of a particular palm flower) was once a popular dessert. In Haiti it is often consumed with cassava or regular bread for breakfast.
In Mexico and Central America, avocados are served mixed with white rice, in soups, salads, or on the side of chicken and meat. In Peru, they are consumed with tequeños as mayonnaise, served as a side dish with parrillas, used in salads and sandwiches, or as a whole dish when filled with tuna, shrimp, or chicken. In Chile, it is used as a puree with chicken, hamburgers, and hot dogs; and in slices for celery or lettuce salads. The Chilean version of Caesar salad contains large slices of mature avocado. In Kenya, the avocado is often eaten as a fruit, and is eaten alone, or mixed with other fruits in a fruit salad, or as part of a vegetable salad. In Iran, it is used as a rejuvenating facial cream.
A puree of the fruit was used to thicken and flavor the liqueur Advocaat in its original recipe, made by the Dutch population of Suriname and Recife, with the name deriving from the same source.
Avocado slices are frequently added to hamburgers, tortas, hot dogs, and carne asada. Avocado can be combined with eggs (in scrambled eggs, tortillas or omelettes), and is a key ingredient in California rolls and other makizushi (“maki”, or rolled sushi). In southern Africa, Avocado Ritz is a common dish.
In the United Kingdom, the avocado became widely available in the 1960s when it was introduced by Marks and Spencer under the name ‘avocado pear’. However, many customers tried to use it as a dessert ingredient like other pears (e.g. with custard), and complained to the store that it was inedible. As a result, Marks and Spencer dropped the word ‘pear’ and labelled it simply ‘avocado’.
Nutritional value
Avocados have diverse fats. For a typical avocado:
About 75% of an avocado’s calories come from fat, most of which is monounsaturated fat.
Avocados also have 60% more potassium than bananas. They are rich in B vitamins, as well as vitamin E and vitamin K.
Avocados have a high fiber content among fruits – including 75% insoluble and 25% soluble fiber. A fatty triol (fatty alcohol) with one double bond, avocadene (16-heptadecene-1,2,4-triol), is found in avocado.
High avocado intake was shown in one study to lower blood cholesterol levels. Specifically, after a seven-day diet rich in avocados, mild hypercholesterolemia patients showed a 17% decrease in total serum cholesterol levels. These subjects also showed a 22% decrease in both LDL (harmful cholesterol) and triglyceride levels and 11% increase in HDL (helpful cholesterol) levels. Additionally a Japanese team synthesised the four chiral components, and identified (2R, 4R)-16-heptadecene-1, 2, 4-triol as a natural antibacterial component.
Avocado fruits have potential mouth-anticancer activity due to a combination of specific aliphatic acetogenins. Extracts of P. americana have been traditionally used to treat hypertension and diabetes mellitus.
Toxicity to animals
Avocado leaves, bark, skin, or pit are documented to be harmful to animals; cats, dogs, cattle, goats, rabbits, rats, birds, fish, and horses can be severely harmed or even killed when they consume them. The avocado fruit is poisonous to some birds, and the American Society for the Prevention of Cruelty to Animals (ASPCA) lists it as toxic to many animals including cats, dogs, and horses. Avocado is an ingredient in AvoDerm dog food and cat food. However, the ASPCA has declined to say whether this food is safe or not.
Avocado leaves contain a toxic fatty acid derivative, persin, which in sufficient quantity can cause equine colic and, without veterinary treatment, death. The symptoms include gastrointestinal irritation, vomiting, diarrhoea, respiratory distress, congestion, fluid accumulation around the tissues of the heart, and even death. Birds also seem to be particularly sensitive to this toxic compound. Feeding avocados or guacamole to any nonhuman animal should be avoided completely. Negative effects in humans seem to be primarily in allergic individuals.